老鲁问答|语法是一种现实，不是一种规则
什么是英语语法？
一般的语法书都说，语法就是对语言运用中语句结构的规定。
但，从教学的英语语法是英语语言研究者对英语语言运用的现实进行总结，而形成的对英语语句结构的归纳性分析，而不是语法书作者个人规定的一系列语法规则。
这说明：
1、英语语法不是中国语法专家说了算的，甚至也不是英语国家语法专家说了算的，而是用英语的人运用英语的一种现实。所谓的语法“规则”其实只是对语法运用现实的总结归纳的一些现象性描述。
2、英语语法不是我们中国的英语老师对英语运用规则的理解，而是英语语言研究者对语言运用现实的总结。
我们看到我们的一些英语老师，喜欢基于自己的理解，从中国的英语语法研究者写的各种英语语法书中，非常认真地总结出一些他们对英语运用规则的发现，甚至编成各种所谓的口诀、歌谣，而这些与真实的英语语言运用却往往存在很大的不一致。
如我们习惯上认为“定语从句在句中起定语作用，修饰某一名词或代词”，但是，我们看到，英国的英语语言研究者编写的The Cambridge Grammar of English中，却没有相应的定义，甚至没有定语从句这一概念，我们所说的定语从句只是作为关系从句中的一种起修饰作用的从句，如：
The people I work with are nice.
(I work with is a relative clause functioning as postmodifier in the noun phrase.)
这里我们可以看到，post-modifier不只是定语从句，各种非谓语动词、副词和介词短语，都可以作postmodifier。
The main types of postmodifier are:
• full relative clauses: the newspaper I have always bought; the fighting which accompanies every international football match between the two countries
• -ing relative clauses: that short fat man walking through the shop
•-ed relative clauses: the six Cuban nationals held in custody by rebel soldiers
• to-infinitive relative clauses: We had a long journey to make before nightfall.
• prepositional phrases: Those piles on the floor are exam papers from last year.
• adjective phrases which include a complement of the adjective: a jacket similar to yours; parents eager to support their children’s efforts
从学习的角度看，汉语中的定语都是在被修饰词前面，如果一定要使用“定语从句”这个概念进行教学，势必还需要花大气力让学生记住“英语定语从句在被修饰词后面”，这很可能导致中国学生问这样的问题：“既然在后面，为什么还是定语”？
所以，我以为，不如按照英语国家的语法专家的归纳总结，将其定义为“作为postmodifier的关系从句”，这一概念很便于理解，也是非常直接的位置说明，甚至也清楚地彰显出与功能相同者的关联性。
这一例子说明，英语语法教学不宜从规则入手，而应从英语运用的现实入手。
以下两段文字或许可以帮助您更准确地理解我的这一想法。（说心里话，这些文字事实上的权威性、和接受心理上权威性，是我永远无法达到的。所以，以此为证，说明拙见不虚。）
Descriptive versus prescriptive approach
Excerpt from The Cambridge Grammar of English
A descriptive approach to grammar is based on observations of usage; it states how people use the grammar of a language. A prescriptive approach to grammar is based on the idea that some forms are more‘correct’ or more associated with ‘good usage’ than others. Prescriptive rules are often social rules that are believed to mark out a speaker or writer as educated or as belonging to a particular social class. Examples of prescriptive rules are:
Do not end a sentence with a preposition.(e.g. Do not say This is something you should not be involved in; say This is something in which you should not be involved)
Do not split an infinitive.(e.g. Do not say I expect to shortly welcome him here; say I expect to welcome him here shortly)
Examples are given throughout the book of contexts of use in which prescriptive rules do or do not apply, where this is useful to language learners. The book also contains a number of specially written panels that highlight common prescriptive rules, discuss attitudes to the rules and examine how they do or do not apply in different contexts of use( for example 337).
The main approach taken in this book is descriptive. The emphasis throughout the book is on describing the ways in which speakers and writers of English use the language to communicate with one another, as evidenced in large numbers of spoken and written texts from all over the British English community.
The approach taken is, we believe,compatible with a pedagogical grammar which is written primarily for advanced learners of English. It is therefore important that learners are aware of the social importance which attaches to certain prescriptive rules while at the same time being aware of the way in which English is used by real speakers and writers of the language. Issues relevant to a learner’s grammar are explored further at several places below.
Grammar rules: deterministic and probabilistic
The general lay person’s perspective is that grammar is about rules of speaking and writing, but not all ‘rules’ given by grammarians are of the same kind.
Some rules are deterministic, that is, they are rules which always apply. For example, the definite article always comes before the noun (we say the cup, not cup the), or indicative third person singular present tense lexical verbs always end in -s (we say she works, not she work). Other rules are probabilistic, that is to say, they state what is most likely or least likely to apply in particular circumstances. For example,in the overwhelming majority of cases, a relative pronoun (e.g. who, which,that) must be used to refer to the subject of a relative clause:
We met a woman who had lived in Berlin during the 1980s.
However, in informal spoken styles, the relative pronoun may often be omitted, especially after a there construction:
There was a shop in the village sold home-made ice cream.(or: There was a shop in the village which/that sold home-made ice cream.)
It is not a rule that the relative pronoun must be omitted; it can be omitted. The rules concerning its use are therefore probabilistic (it is most probable in most cases that the relative pronoun will be used). In this book, many of the rules given are probabilistic, since they are based on observations of what is most likely and least likely in different contexts in real spoken and written data.